Knee synovitis

Definition

Knee synovitis is an inflammation of the joint’s synovial membrane, accompanied by an effusion accumulation. It can be aseptic or infectious, acute or chronic. The cause of the development of the disease becomes a closed or open trauma, metabolic disorders, arthrosis, arthritis, hemophilia, or allergies. Non-infectious synovitis is manifested by an increase in the volume of the joint and aching pain; with infectious synovitis, there is an increase in temperature and a pronounced pain syndrome. Ultrasound, MRI, radiography, and other studies are used in the diagnostic process. Treatment is usually conservative. 

General information

Synovitis of the knee joint is an inflammation of the inner layer that results in fluid accumulating in the joint. It most often develops as a result of trauma, with synovitis in knee osteoarthritis being the second most common. Traumatic synovitis is usually detected in young and middle-aged people and is caused by arthrosis in elderly patients. Both acute and chronic courses with periodic exacerbations are possible.

Synovitis of the knee joint is not an independent disease; it only results from other general or local pathological processes. At the same time, synovitis, especially infectious or frequently recurrent non-infectious, can aggravate the course of the underlying disease, cause the formation of hypertrophic villi, scarring, thickening, sclerosing or petrification of synovial membrane areas. Changes in the inner lining of the joint can have a negative impact on the condition of other intra-articular structures.

Causes

Usually, the cells of the inner lining of the joint produce a small amount of fluid. This fluid acts as a lubricant, making it easier for the intra-articular structures to slide against each other. In addition, synovial fluid supplies nutrients to the articular cartilage. In synovitis, the synovial membrane cells begin to secrete more fluid; its composition varies depending on the type of inflammation. An effusion is formed in the joint.

Traumatic injuries, infections, congenital and acquired pathological changes of the joint and periarticular tissues, allergic reactions, metabolic disorders, endocrine diseases, autoimmune diseases, and hemophilia can provoke inflammation of the synovial membrane.

Infection can penetrate the joint cavity from the external environment (e.g., when the joint is wounded), from neighboring tissues (with nearby infected abrasions and wounds, boils, abscesses, phlegmon, etc.), with the blood or lymph flow (in remote foci of infection). In most cases, the causative agent of infectious synovitis of the knee joint is non-specific festering microorganisms: streptococci, staphylococci, or pneumococci. In some cases, specific infectious synovitis caused by pale treponema (in syphilis) or mycobacterium tuberculosis is detected.

Classification

The process can be acute or chronic. In the second case, exacerbations alternate with more or less long remissions. Given the nature of inflammation in traumatology and orthopedics, two main types of synovitis of the knee joint are distinguished: non-infectious and infectious. Non-infectious inflammation is aseptic in nature, while in infectious inflammation, pathogenic bacteria are involved.

Symptoms of synovitis

Acute aseptic synovitis

In acute aseptic synovitis, the joint increases in volume within a few hours or days. Often, there is a feeling of pressure; there may be non-intense pain that increases with movement. On examination, there is a disturbance in the shape of the joint, smoothing the contours and bulging on the sides of the patella. There may be a slight swelling of soft tissues. The presence, localization, and severity of pain on palpation are determined by the underlying pathology. Fluctuation and balloting of the patella are revealed: when pressure is applied to the patella, it sinks into the joint, and when pressure is stopped, it “pops up.” In some cases, there is weakness, malaise and slight fever.

The severity of symptoms depends on the amount of fluid in the joint. When a large amount of effusion accumulates, pain and a feeling of pressure increase, swelling increases, the skin of the joint becomes shiny, and sometimes there is hyperemia. The nature of the effusion is usually determined by the cause of the disease. In traumatic injuries and hemophilia, the effusion is hemorrhagic (the fluid is colored with blood); in other aseptic synovitis – serous (initially, the fluid is transparent, with a straw color, later there is some darkening, the effusion becomes yellow and less transparent).

Chronic aseptic synovitis.

Chronic aseptic synovitis runs in waves, with exacerbations alternating with remissions. During exacerbation, the picture resembles acute aseptic synovitis, but the symptomatology is often smoothed and less vivid. In some cases, a small amount of effusion is observed. Pain and limitation of movement in the joint are due to the thickening of the synovial membrane. The severity of symptoms during remission depends on the underlying disease and the duration and frequency of exacerbations of synovitis. Limitation of movement, dull aching pain, and rapid fatigue when walking may be observed.

Acute purulent synovitis

Acute purulent synovitis is characterized by pronounced general and local symptoms. The joint is enlarged in volume, and sharp pain, local hyperemia, and hyperthermia are noted. Movement is sharply limited or almost impossible because of the intense pain syndrome. The general condition is disturbed; weakness, chills, brokenness, nausea, and rapid fatigue appear. Body temperature is elevated to febrile digits. In severe cases, hallucinations, delirium, and confusion are possible. Palpation of the joint is sharply painful. The infection spreads to other joint structures without treatment, and acute purulent arthritis occurs.

Diagnosis

Diagnosis is performed by a traumatologist or rheumatologist. To confirm the diagnosis and identify the underlying disease, they prescribe:

• Knee X-ray
• Knee arthroscopy
• Knee CT
• MRI of the knee joint
• Knee ultrasound
• Depending on the form of synovitis, various microscopic and immunologic examinations of the aspirate are performed, and sowing on nutrient media is performed.
• Synovial biopsy

If necessary, the patient is referred for consultation to an allergist, infectious disease specialist, hematologist, endocrinologist, or other specialist.

Treatment of synovitis of the knee joint

Conservative treatment

Treatment of aseptic synovitis is usually outpatient and includes puncture with evacuation of the effusion and immobilization of the limb with a plaster cast, knee brace, or pressure bandage for 5-7 days. Prolonged immobilization in synovitis is not indicated because prolonged lack of movement can cause joint stiffness. Patients are prescribed therapeutic exercises, microwave therapy, electromagnetic therapy, and electrophoresis with anti-inflammatory drugs. 

In recurrent synovitis, therapy with glucocorticoids, heparin, ibuprofen, and indomethacin is prescribed. During the period of exacerbation of 3-4 days, patients are referred to physiotherapeutic procedures: phonophoresis with corticosteroid drugs, magnetic therapy, electrophoresis with ketoprofen, and heparin. It should be borne in mind that heparin is contraindicated immediately after trauma and surgery, as well as in coagulation disorders.

In chronic synovitis with marked infiltration of the synovial membrane, proteolytic enzyme inhibitors are used, and aprotinin and small doses of corticosteroids are injected into the joint.

Surgical treatment

Pathogenetic treatment of traumatic synovitis involves restoring normal anatomical relationships in the joint. Therapeutic tactics are determined individually in each case, taking into account the severity of posttraumatic changes, the severity of secondary disorders (posttraumatic arthrosis), the prospects and risks of surgical intervention, and other factors. When indicated, surgeries are performed: reconstructive interventions on bones, meniscus resection, ligament repair, etc. In the postoperative period, drug correction of local metabolic disorders and rehabilitation measures are carried out.

In case of irreversible changes in the synovial membrane (sclerosis, formation of petrificates, and hypertrophied villi) due to chronic synovitis, surgical intervention is performed – partial, subtotal, or total synovectomy. In the postoperative period, immobilization is performed, and antibiotics, analgesics, and physical procedures are prescribed.

All these treatment options are available in more than 790 hospitals worldwide (https://doctor.global/results/diseases/knee-synovitis). For example, Arthroscopic synovectomy of the knee joint can be performed in these countries at following approximate prices:

Turkey $2.6 K in 26 clinics

Germany $10.6 K in 43 clinics

China $11.4 K in 8 clinics

United States $15.4 K in 17 clinics

Israel $31.7 K in 16 clinics.